r f campbell



R. F. CAMPBELL Filed July 29, 1926 MM! m M 6 HEATING CONTROL ATTACHMENT FOR HOT WATER BOILERS Jan. 27, 1931.

Patented Jan. 27, 1931 ROBERT I. CAMPBELL, OF MIAMI, FLORIDA KEATING CONTROL ATTACHMENT FOR HOT-WATER 30ILEZRS Application filed July 29,

whereby heat is wasted and the expense oi."

maintaining the hot water supply materially and unnecessarlly increases.

The object of my invention, broadly stated,

is to provide an attachment for domestic hot water boiler which can be secured to any standand boiler and so positioned on the boiler as to control the percentage of volumn of water to be heated in the tank. That is to say, if one requires but ten gallons of hot water the attachment can be so adjusted on the boiler that the'supply of the heating medium is automatically cut off after ten gallons have been heated. In some instances it may be cheaper and desirable to operate an alarm instead of cutting off the heating medium after the predeteri'nined amount of water has been heated in the boiler. v This, of course, is optional and controlled by the circumstances of each installation.

My invention consists, broadly stated, of an attachment adapted to be adjustably secured to the outside of a domestic hot water tank, said attachment carrying a heat responsive mechanism in contact with or close proximity to the outer face of the hot water boiler, said heat responsive mechanism being suitably connected with the switch or an alarm.

In the drawings: I Figure 1 is a front elevation of a domestic hot water boiler partly in section with my invention in an adjustable position thereon.

Figure 2 is a detail sectional view of my invent-ion with a solenoid in the circuit.

Figure 3 is a diagrammatic view illustrating my invention with a ball circuit.

The reference numeral 1 designates a domestic hot water tank or boiler which may be 1828. Serial No. 125,772.

of any approved construction and of any desired capacity.

My improved attachment for hot water boilers consists of a ring 2 which is adapted to be ad ustably secured at any point between the top and bottom of the boiler by means of a set screw, pr other suitable device 3. A suitable case 4, preferably made of aluminum is secured to the ring 2 b means of the set screws 5 ,which enter suitab e recesses in the cup or case 4. This cup or case 4 may be made with one of its side walls concaved to conform tothe perimeter of the tank 1 as will be readily understood, whereby a materiallv larger area of contact is afforded between the wall of the tank 1 and the cup 4. A case or cup 4 is pro vided with a cap or cover 6 which may also be made of aluminum and have one of its side walls concave to conform with the concave wall of the cup 4. This cap has flanges 7 which project down in the case 4 and rest snugly on top of the shoulders of the mercury tube 8 which is seated in the case or cup 4. If desired or if thought necessary, a suitable pad may be placed on the shoulders of the mcrcurv tube to prevent the flange 7 of the cap 6 from damaging the tube, yet holding the tube snugly and firmly in place by the cover. The cap ti is provided with a-screw thread opening in which is adj ustably seated a contact screw S).

This screw is properly adjusted relative to the mercury tube so as to complete a circuit when the mercury is expanded. The cap 6 is securely fastened to the cup or casing 4 by means of a screw 10. In this connection it will be noted that the contact screw 9 is not insulated from the aluminum cap 6.

Take for example a forty gallon tank 1 and assuming that only ten gallons of hot water are necessary or desired, the band 2 with the cup 4 and its associate parts are adjusted to a point from the top about one-fourth the length of-the tank, secured in that position after which the heating medium is turned on and in the case of an electric current the circuit will function as follows:

When the hot water insideof the tank 1 reaches down as far as a point opposite the mercury tube 8 the heat from the water passing through the metal wall of the tank 1 will be conveyed to the mercury tube 8 and the inercur will expand and 'make contact with the sai screw 9, then we have a circuit from p the battery 11 through the bell 12, lead 13 to cover 6 and set screw 9, the set screw 9 not' being insulated from the cover 6, the current will pass down through set screw 9 which due to the ex ansion of the mercury is making contact with the mercur the current going through the mercury to cad 14: (which is in direct contact with the mercury at'all times, but is securely insulated where it passes through the cup 4) and hack to the battery which will complete the'circuit and cause the bell to ring giving notice that the required amount or water has been heated.

When an electric current is to be used for heating the water the switch 15 will he de signed to function on the same control which operates the switch controlling the heating filament 17. In this way the alarm will he set at all times that the heatin' current is passing through the filament. course, it will be understood that the two switches are to he carefully insulated from each other so that the two electric circuits will have no connection, but at the same time the same knob l6- water to be heated in said tan edge of which is concaved to lit the boiler,

flanges depending from the cap into the casing-pa mercury tube in the casing with which saidfianges contact, a contact screw carried by the cap coacting with the mercur and e ectric circuit controllin means inc uding said screw and governed y contraction oi the m'ercur, In testimony whereof I aflix my si nature.

ROBERT F. CAMPBELL.

or lever that operates one will also operate the other.

Such an arrangement of the two switches will insure the settini of the alarm at all times that the water is eing heated, and will facilitate the opening of the alarm circuit when it is not being used.

The size and shape of the mercury tuhe 8 will vary depending on the sensitiveness desired.

Referring to Figure 2: Pushing the solenoid 15' down makes contact at 18 and when heat expands mercury 8' to contact with screw 9 the circuit is complete through the load 13 and bell 12 back to solenoid 15. After there is contact between the mercury and the contact screw 9 the pawl or'othcr similar device 19 holds the solenoid plun er 20 in elevated position out of contact with the contacts 18. By this wiring the alarm 12 is first sounded after the predetermined amount of water has been heated after which the solenoid core is elevated and the circuit broken. The user of the attachment then will disconnect the pawl 19 from the solenoid core 20 and restore the system to operative position.

In Figure 3 I have shown my invention specially adapted for use in connection with the commercial gas heater and from the description given in connection with the other figures it is thought that the operation is obvious. In Figure 3, 21 is thevgas heater. The bell circuit shown in Figure 3, it is believed, is so simple that no description is necessary for the same.

What I claim is: i

An attachment for domestic hot water expansion and 

